implement quick help dialog

tools/lammps-gui/TODO.md

@@ -2,10 +2,9 @@ LAMMPS-GUI TODO list:
 
 # Short term goals
 
-- add "Help" entry to menu bar. Should open a popup window with a one page description of how to use it. Use HTML or Markdown text.
 - add CTRL-q hotkey to log windows so you can exit the entire application (add do you really want to? dialog to this)
 - add "syntax check" with enabled "-skiprun" flag
-- add settings dialog where certain properties can be set through customizing the LAMMPS command line
+- add multi-tab settings dialog where certain properties can be set through customizing the LAMMPS command line
    + enable/disable OpenMP (via suffix), OPT package, select number of OpenMP threads
    + toggle whether captured screen output should include input file echo
    + select Font

tools/lammps-gui/lammpsgui.cpp

@@ -180,7 +180,6 @@ LammpsGui::LammpsGui(QWidget *parent, const char *filename) :
     } else {
         setWindowTitle(QString("LAMMPS-GUI - *unknown*"));
     }
-
 }
 
 LammpsGui::~LammpsGui()
@@ -620,8 +619,41 @@ void LammpsGui::about()
 
 void LammpsGui::help()
 {
-    QString helpmsg = "This is LAMMPS-GUI version " LAMMPS_GUI_VERSION;
-    QMessageBox::information(this, "LAMMPS-GUI Help", helpmsg);
+    QMessageBox::information(
+        this, "LAMMPS-GUI Quick Help",
+        "<div>This is LAMMPS-GUI version " LAMMPS_GUI_VERSION "</i></div><br><br>"
+        "<b>Overview</b>"
+        "<div align=\"justify\">LAMMPS GUI is a graphical text editor that is "
+        "linked to the LAMMPS library and thus can run LAMMPS directly using "
+        "the contents of the text buffer as input through the LAMMPS C-library "
+        "interface. This makes it convenient to use for beginners and during "
+        "tutorials</div><br><br>"
+        "<b>Features</b>"
+        "<div align=\"justify\">The main window of the LAMMPS GUI is a text "
+        "editor window with syntax highlighting. The output of a LAMMPS run is "
+        "captured and displayed in a log window. The log window is updated "
+        "regularly during the run, as is a progress bar in the main window. "
+        "After the simulation is finished, an image of the simulated system "
+        "can be created and shown (and saved) in image viewer window.  Ongoing "
+        "runs can be stopped at the next run iteration.</div><br>"
+        "<div align=\"justify\">When opening a file, the editor will determine "
+        "the directory where the input file resides and switch its current "
+        "working directory to that same folder. Many LAMMPS inputs contain "
+        "commands that read other files, typically from the folder as the "
+        "input file. The GUI will show its current working directory. "
+        "In addition to using the menu, the editor window also receive files "
+        "as the first command line argument or via drag-n-drop from a "
+        "graphical file manager GUI or a desktop environment.</div><br>"
+        "<div align=\"justify\">Almost all commands are accessible via hotkeys. "
+        "Which those hotkeys are, is shown next to the entries in the menus. "
+        "Log and image viewer windows can be closed with CTRL-W (or Command-W "
+        "on macOS).</div><br>"
+        "<div align=\"justify\">The 'About LAMMPS' dialog will show the "
+        "LAMMPS version and the features included into the LAMMPS library "
+        "linked to the LAMMPS GUI.<br><br>"
+        "Due to its nature as a graphical application, it is <b>not</b> "
+        "possible to use the LAMMPS GUI in parallel with MPI, but OpenMP "
+        "multi-threading is available.</div>");
 }
 
 void LammpsGui::manual()

tools/lammps-gui/lammpsgui.ui

@@ -311,10 +311,10 @@
      <normaloff>.</normaloff>.</iconset>
    </property>
    <property name="text">
-    <string>&amp;Help</string>
+    <string>Quick &amp;Help</string>
    </property>
    <property name="toolTip">
-    <string>Short Help</string>
+    <string>Quick Help</string>
    </property>
   </action>
   <action name="actionEdit_Preferences">